The present invention relates to an oil free screw compressor capable of controlling the speed of a cooling fan, and in particular to an oil free screw compressor capable of appropriately maintaining temperatures of compressed air and lubrication oil in response to variation in a surrounding atmosphere.
There has been known an air-cooled oil-free screw compressor for compressing air by a pair of male and female screw rotors which can be rotated in a noncontact and nonlubricated manner. The air-cooled oil-free screw compressor incorporates an air-cooling type cooler for cooling lubrication oil for lubricating bearings, gears and the like, and compressed air, having the configuration that the atmospheric air is taken thereinto by means of a fan in order to carry out heat-exchange with the lubrication oil and the compressed air (Refer to, for example, JP-A-01-116297).